As a so-called writable optical recording medium, there has been known an optical recording medium which comprises a transparent substrate, a light absorbing layer comprising an organic coloring matter (or colorant) such as a cyanine type and a phthalocyanine type, a light reflection layer formed on the light absorbing layer, and a protection layer disposed on the light reflection layer. In the optical recording medium having such a structure, a laser light (or laser beam) is supplied thereto from the transparent substrate side thereof and the laser light is concentrated (or focused) on a minute area of the light absorbing layer so that it is converted into heat energy. As a result, the thus irradiated portion of the light absorbing layer is caused to have a different state or configuration (e.g., a pit is formed in such a portion), thereby to effect writing. On the other hand, a laser light (or laser beam) for reading is supplied to such an optical recording medium from the transparent substrate side thereof and is reflected by the light reflection layer. At this time, the resultant contrast between the quantity of the reflected light in a portion having the above pit formed therein and the quantity of the reflected light in a portion having no pit formed therein is detected and converted into an electric signal, thereby to effect reading.
In the conventional optical recording medium, however, the above protection layer which is disposed for the purpose of preventing the deterioration or scratch which can occur in the light absorbing layer and/or the light reflection layer, has been formed by applying a resin material such as an ultraviolet ray curing (or hardening) resin and a solvent type resin on the light reflection layer and hardening the resultant coating. In the conventional optical recording medium having the above protection layer, however, there is posed a problem such that the light absorbing layer and the light reflection layer are not sufficiently protected from the external force as described above.
More specifically, since the conventional protection layer has an insufficient humidity resistance (or resistance to humidity), it causes a crack or bonding failure (or local float or rise). As a result, there is posed a problem such that the electric potential in the mirror surface portion (Ro), the electric potential in the land/groove portion (I.sub.l and/or I.sub.g), the tracking error potential (TE), etc., may be varied or decreased.